Signs of knee infection may include fever, fatigue, swelling, redness, localized warmth, drainage of fluid from the knee, or a recurrence of pain or stiffness after full post-operative recovery has been achieved. An x-ray or bone scan can also help your surgeon determine if there is an infection.
If there is visible fluid coming from the surgical site or incision, your surgeon may recommend a culture. A sample of the fluid is collected and tested in a lab to determine what bacteria are present. Blood tests and needle aspiration of fluid surrounding the joint may also be needed to definitively diagnose an infection (Parvizi, et al., 2018).